The invention relates generally to swivelable chairs, and more particularly to a swivelable chair that has excellent resistance to corrosion and fouling, even under the harshest environmental conditions.
The invention is a swivelable chair that can function and resist deterioration even under the harshest outdoor conditions. These harsh conditions are most easily identified with the beach, because not only are these aging and oxidative issues associated with sunlight, but also the effects of saltwater, saltwater filled air, wind and sand. The situation is particularly aggravating for moving part components, because even materials that exhibit good resistance to oxidation, are often effected by abrasion. A good example of a corrosion resistant metal is aluminum. Aluminum is effected very little by the beach environ, however in applications where there is surface against surface movement, as in the case of a hinge, the aluminum hinge generates fine black dust filings as the two aluminum surfaces slide across each other. The salt in saltwater forms crystalline deposits as the water dries, leaving behind a very hard substance, which acts as an abrasive against the aluminum. Also, when aluminum is in contact with other metals, it generates strong electromotive forces (like in batteries) which can accelerate the destruction of the other metal. Saltwater and sand are particularly corrosive to bearings on beach chairs. Wunderlich, in U.S. Pat. No. 4,842,335, discloses a beach chair having a PVC frame, where the seat swivels on a planar bearing. While the bearing is protected pretty well from sand, the bearing does not have an air tight seal, and minute salt deposits can rapidly form in the presence of a sea mist. Additionally, and even more corrosive, saltwater can cause the metal bearing to rapidly rust. Even bearings packed in grease will rust unless repacked on a regular cycle. To the user of a chair, the grease can be as troublesome as the black filings or the rust.
What is needed is a chair that that doesn""t have any hinges that can rust or generate black filings or become packed with sand or exude grease. Furthermore, what is desired is a chair that is light enough that it can be easily carried. Additional requirements include a chair that can swivel, where the swivel is virtually maintenance free, unaffected by a saltwater environment, and where the swivel does not unduly add to the overall cost or weight of the chair. Of course, the swivel should not exude grease or generate black filings, and should perform even when encrusted by sand and salt.
A beach chair must have a base with sufficient surface area to prevent the chair from sinking into the sand. The Wunderlich""s U.S. Pat. No. 4,842,335 discloses an elegant solution this problem. In lieu of traditional legs, the chair rests on a ring, that, like the chair, is constructed of PVC tubing. The circular base is a very stable platform, which is needed to swivel smoothly.
Gomes"" U.S. Pat. No. 4,482,186 addresses the issue of devising a hinge that does not generate black filings as the hinge is worked open and closed. The moving components of the frame are separated by plastic washer to keep the surfaces from rubbing against each other. The chairs disclosed by both Gomes and Wunderlich have a frame with a fabric stretched across the frame. The fabric is not secured from sideways movement except at the top of the back and the front of the seat.
Meek describes a method for making an xe2x80x9cAntifriction Nylon Memberxe2x80x9d in U.S. Pat. No. 4,076,347. His patent discloses how Nylon(copyright) can be compounded with lubricants to make the Nylon(copyright) self-lubricating. The anticipated application for the compounded Nylon(copyright) is as a component in the fabrication of axial bearings.
A non-squeaky hinge is disclosed by Bishing in U.S. Pat. No. 4,630,332. The knuckles of the hinge are made of acetal, a hard plastic, and the pin is made of Nylon, a more elastic plastic. The hinge is resistant to aging and would not generate black filings.
The RBF company offers a beach chair, trademarked the Suntracker(copyright), that like Wunderlich""s chair, also has a planar bearing. RBF""s Suntracker addresses the sand issue by enclosing the ball bearings in a polyethylene ring. The metal plate housing the planar bearing is constructed of zinc coated steel. These prophylactic measures, no doubt would appear to slow down corrosion, however marine fittings, particularly running rigging, generally employ type 316 stainless steel. The addition of zinc would slow down air oxidation, but would create greater electrical anisotropy between metals of differing electrical potential, which could aggravate in situ oxidation. Also, like Wunderlick""s chair, the preferred base is a ring.
The invention is a chair having excellent resistance to the corrosive and abrasive elements of a saltwater beach. Furthermore, the invention is a chair that has a stable platform on soft sand, and is of sufficient resistance to sand and surf that it can be used in shallow waters. The chair is swivelable, allowing the user to change his angular orientation without leaving the chair, by simply applying a tangential force with an arm or leg. In a preferred embodiment the angle of incline of the chair back is adjustable, such that the user can reversibly adjust his support from a posture of sitting to reclined.
The chair consists of a seat, an underpinningxe2x80x94which is fastened to and supports the seat, a swivelable meansxe2x80x94which is fastened to and supports the underpinning, and a basexe2x80x94which is fastened to and supports the swivelable means.
The seat is the uppermost horizontal portion of the chair. The seat is a shelf, a shelf with a cushion, or preferably a frame with a flexible covering. The frame is preferably constructed of sectional elements of tubing that are connected with coupling elements to form the desired shape. The preferred shape of the frame is substantially rectangular. The sectional elements are substantially straight. The coupling elements are used to extend or corner two sectional elements, and a split coupling element is used to join two sectional elements to a third. Examples of split coupling elements are a T and a Y coupling element. The frame of the seat has a rear sectional element, a front sectional element, a right sectional element and a left sectional element. The flexible covering is preferably a cloth or a webbing or a combination thereof. The flexible covering is preferably selected from materials known to have good resistance to sunlight. Polyesters, acrylics and polyamides, such as Nylon(copyright) are well known in the art. Kevlar(copyright), a polyimide and Fiberglas(copyright) are also recognized as having good resistance to sunlight, Blends of any of the above are also anticipated. Less preferable, but less expensive synthetic materials, like polyvinyl materials such as polyethylene, plasticized polyvinylchloride and polypropylene will also work, as will natural fibers such as cotton.
The frame is preferably constructed of pvc tubing, however aluminum tubing will also work.
The chair can optionally, be fitted with a back preferably of similar construction to the seat. The flexible covering is attached to the seat frame and the back frame.
The chair can also have armrests, wherein it is preferred that the top most surface of armrest is comprised of wood.
The chair can optionally have an adjustable recline feature, which enables the back to be reversibly adjusted backward. This feature is comprised of an apparatus for setting the angle of recline, and a hinge assembly that enables the back to pivot on the rear sectional element. The angle is set using a notched slide on the underside of the right and left armrest. This is a conventional adjustable recline apparatus for chaise beach recliners. The hinge assembly is novel. The left and right ends of the rear sectional element are fitted with a T-shaped coupling element and held together with an interior tie bar. The T-shaped split couplings are then fastened to the ends of the tubing comprising the side elements of the back frame. The combination of sectional elements and coupling elements forms a left hinge and a right hinge having no metal parts. The novel hinge has no metal parts, and it is substantially free of any openings where sand can collect.
The underpinning is an assembly for attaching the seat to the swivelable means. The underpinning provides the support for the seat, and translates the stress weight of the chair""s occupant to the swivelable means. Like the seat, the preferred structure is a tubular frame of pvc. Typically, the seat is supported via left and the right sectional elements at either one or two points per element. Alternatively, the left and the right sectional elements and the rear sectional element can be supported at one point per element. Additional support is generally not needed. The underpinning consists of one or more heavy gauge sectional element and the corresponding requist number of split coupling elements. The heavy gauge sectional element is fastened to the top of the swivelable means and bends upward with a U shape, where it is connected to the split coupling element. The split coupling element is spliced into the receiving sectional element of the frame.
The swivelable means is a unique planar bearing, where the planar bearing consists of a pair of superimposed horizontal disks which are fastened together with an axial longitudinal pin. There are no ball bearings, or other moving elements between the disks. There are no sealing rings. The disks have a flush fit. The pair of disks consists of an upper disk and a lower disk. The upper disk has a bottom, overcut face with a low friction first surface and a top face that is fitted with hardware for mounting the heavy gauge sectional element of the underpinning. The lower disk has an upper, undercut face that has a low friction second surface and a sectional portion that is equipped for mounting the base.
The overcut face on the upper disk is axially aligned with the undercut face of the bottom disk, and positioned face-to-face, such that the overcut face matches and the undercut face. The disks are essentially nested, and therein self-aligning.
It should be noted that the stress weight is spread over the interface face of the superimposed disks, and therefore the frictional resistance between the disks is relatively low. The disks are substantially constructed of an engineering plastic, where a preferred plastic is self-lubricating plastic. The utilization of a self lubricating plastic, such as Nylon(copyright) or Nylon(copyright) compounded with a lubricant further reduces the frictional resistance. It is anticipated that a variety of plastics will be of sufficiently low resistance to fulfill the frictional resistance criterion. The reader is reminded that in the instant invention, under normal operating conditions there will be very little rotation, as contrasted to the operation of most bearings (i.e. a machine turning an axle). Heat build up as a consequence of friction resistance therefore is not a problem.
The base is integral with the lower disk, and a preferred construction is a spoke-ring assembly, where a sectional element of tubing radially emanates from a snug fitting receiving hole in the lower disk. The holes are equidistantly positioned around the bottom disk. The sectional elements, usually four, are orthogonal, and each is capped with T-shaped coupling element. The coupling element is connected to a pair of two curved sectional elements. The connected curved coupling elements form a ring. The ring holds the sectional elements in the bottom disk in position, and therefore a fastening means for the bottom disk is not required. This arrangement of elements facilitates in the manufacturing process, without any loss of performance. A preferred bottom disk is formed with four identical holes that are orthogonal from each other. The base prevents the chair from sinking into soft sand. A 1 inch wide ring that is 18 inches in diameter has a surface area that is approximately 18 times the surface area of 4 legs that are 1 inch in diameter. The additional surface area stabilizes the chair when it is swiveled, and enables the base of the chair to span irregular contours in the sand.
Recapping, the instant invention is a beach chair with a swivelable means. The swivelable means is a planar bearing that is uniquely suitable for the application because the disks are self-centering, the planar bearing has no ball bearings, the surfaces are self lubricating, and nearly the entire planar bearing is constructed of plastic. The preferred plastic is selected for excellent aging properties in a saltwater environment and its slip properties. The superimposition of disks, such that they are aligned with the weight stress, which in this case is the seat and its occupant, optimally distributes the stress across the interface of the disks, therein reducing strain and wear. Where wear does occur, its effect tends to be negligible, because the wear does not bore out the axis of rotation. The top disk is attached to the bottom disk with one axial longitudinal pin. The pin can be a bolt and nut, or any conventional fastening means. The back of the chair is hingedly attached to the seat using sectional elements, coupling elements and a tie bar. This hinged attachment, like the swivelable means, highly resistant to corrosion or clogging with sand. Neither the swivel nor the hinged attachment requires a lubricant to work properly. Nor does either produces black filings as the surfaces side across each other. There are no metals to rust or affect corrosion of a proximal metal. The only problem with this chair, from a marketing stand point, is that like diamond, it will last forever and never needs to be replaced.